This version (27 Oct 2020 13:59) was approved by Michael Hennerich.The Previously approved version (10 Dec 2019 14:31) is available.
Table of Contents
HMC425A Digital Step Attenuator Linux Driver
Supported Devices
Evaluation Boards
Description
This is a Linux industrial I/O (IIO) subsystem driver, targeting Digital Step Attenuator IIO devices with gpio interface. The industrial I/O subsystem provides a unified framework for drivers for many different types of converters and sensors using a number of different physical interfaces (i2c, spi, etc). See IIO for more information.
- HMC425A 0.5 dB LSB GaAs MMIC 6-BIT DIGITAL POSITIVE CONTROL ATTENUATOR, 2.2 - 8.0 GHz
Source Code
Status
Files
| Function | File |
|---|---|
| driver | drivers/iio/amplifiers/hmc425a.c |
| Documentation | Documentation/ABI/testing/sysfs-bus-iio |
Devicetree
properties
compatible:
- enum:
- adi,hmc425a
vcc-supply:
- description: digital voltage regulator (see regulator/regulator.txt)
- maxItems: 1
ctrl-gpios:
- description: Must contain an array of 6 GPIO specifiers, referring to the GPIO pins connected to the control pins V1-V6.
- maxItems: 6
required:
- compatible
- ctrl-gpios
Example
#include <dt-bindings/gpio/gpio.h> &gpio { #address-cells = <1>; #size-cells = <0>; gpio_hmc425a: hmc425a { compatible = "adi,hmc425a"; ctrl-gpios = <&gpio 40 GPIO_ACTIVE_HIGH>, <&gpio 39 GPIO_ACTIVE_HIGH>, <&gpio 38 GPIO_ACTIVE_HIGH>, <&gpio 37 GPIO_ACTIVE_HIGH>, <&gpio 36 GPIO_ACTIVE_HIGH>, <&gpio 35 GPIO_ACTIVE_HIGH>; vcc-supply = <&foo>; }; }
Adding Linux driver support
Configure kernel with “make menuconfig” (alternatively use “make xconfig” or “make qconfig”)
The HMC425A Driver depends on CONFIG_GPIOLIB
Linux Kernel Configuration
Device Drivers --->
<*> Industrial I/O support --->
--- Industrial I/O support
Amplifiers --->
<*> Analog Devices HMC425A DSA
Hardware configuration
Driver testing
Each and every IIO device, typically a hardware chip, has a device folder under /sys/bus/iio/devices/iio:deviceX. Where X is the IIO index of the device. Under every of these directory folders reside a set of files, depending on the characteristics and features of the hardware device in question. These files are consistently generalized and documented in the IIO ABI documentation. In order to determine which IIO deviceX corresponds to which hardware device, the user can read the name file /sys/bus/iio/devices/iio:deviceX/name. In case the sequence in which the iio device drivers are loaded/registered is constant, the numbering is constant and may be known in advance.
This specifies any shell prompt running on the target
root:/> cd /sys/bus/iio/devices/ root:/sys/bus/iio/devices> ls iio:device0 root:/sys/bus/iio/devices> iio:device0 root:/> ls -l drwxr-xr-x 2 root root 0 Jan 1 00:00 . drwxr-xr-x 3 root root 0 Jan 1 00:00 .. -r--r--r-- 1 root root 4096 Jan 1 00:00 dev -r--r--r-- 1 root root 4096 Jan 1 00:00 name -rw-r--r-- 1 root root 4096 Jan 1 00:00 out_voltage0_hardwaregain lrwxrwxrwx 1 root root 0 Jan 1 00:00 subsystem -> ../../../../../../../../../bus/iio -rw-r--r-- 1 root root 4096 Jan 1 00:00 uevent
Show device name
This specifies any shell prompt running on the target
root:/> cd /sys/bus/iio/devices/iio\:device0/ root:/> cat name hmc425a
Set ChannelY Gain
/sys/bus/iio/devices/iio:deviceX/out_voltageY_hardwaregain
Hardware applied gain factor. If shared across all channels, <type>_hardwaregain is used.
This specifies any shell prompt running on the target
root:/> cat out_voltage0_hardwaregain -31.500000 dB root:/> echo -10 > out_voltage0_hardwaregain root:/> cat out_voltage0_hardwaregain -10.000000 dB
More Information
- IIO mailing list: linux [dash] iio [at] vger [dot] kernel [dot] org
resources/tools-software/linux-drivers/iio-amplifiers/hmc425a.txt · Last modified: 27 Oct 2020 13:59 by Michael Hennerich